package com.bookdao.oasis.common.framework.web;

import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.UnsupportedEncodingException;
import java.nio.charset.Charset;
import java.util.ArrayList;
import java.util.List;

import org.springframework.http.HttpInputMessage;
import org.springframework.http.HttpOutputMessage;
import org.springframework.http.MediaType;
import org.springframework.http.converter.AbstractHttpMessageConverter;
import org.springframework.http.converter.HttpMessageNotReadableException;
import org.springframework.http.converter.HttpMessageNotWritableException;
import org.springframework.util.FileCopyUtils;

public class UTF8StringHttpMessageConverter extends  AbstractHttpMessageConverter<String> { 
 
    public static final Charset DEFAULT_CHARSET = Charset.forName("UTF-8"); 
    private final List<Charset> availableCharsets; 
 
    public UTF8StringHttpMessageConverter() { 
        this(DEFAULT_CHARSET); 
    } 
 
    public UTF8StringHttpMessageConverter(Charset defaultCharset) { 
        super(new MediaType("text", "plain", defaultCharset), MediaType.ALL); 
        this.availableCharsets = new ArrayList<Charset>(Charset 
                .availableCharsets().values()); 
    } 
 
    @Override 
    protected boolean supports(Class<?> clazz) { 
        return String.class.equals(clazz); 
    } 
 
    @Override 
    protected String readInternal(Class<? extends String> clazz, 
            HttpInputMessage inputMessage) throws IOException, 
            HttpMessageNotReadableException { 
        MediaType contentType = inputMessage.getHeaders().getContentType(); 
        Charset charset = contentType.getCharSet() != null ? contentType 
                .getCharSet() : DEFAULT_CHARSET; 
        return FileCopyUtils.copyToString(new InputStreamReader(inputMessage 
                .getBody(), charset)); 
    } 
 
    @Override 
    protected void writeInternal(String t, HttpOutputMessage outputMessage) 
            throws IOException, HttpMessageNotWritableException { 
        MediaType contentType = outputMessage.getHeaders().getContentType(); 
        Charset charset = contentType.getCharSet() != null ? contentType 
                .getCharSet() : DEFAULT_CHARSET; 
        FileCopyUtils.copy(t, new OutputStreamWriter(outputMessage.getBody(), 
                charset)); 
    } 
 
    protected List<Charset> getAcceptedCharsets() { 
        return this.availableCharsets; 
    } 
     
    @Override 
    protected Long getContentLength(String s, MediaType contentType) { 
        if (contentType != null && contentType.getCharSet() != null) { 
            Charset charset = contentType.getCharSet(); 
            try { 
                return (long) s.getBytes(charset.name()).length; 
            } catch (UnsupportedEncodingException ex) {                 
                throw new InternalError(ex.getMessage()); 
            } 
        } else { 
            return null; 
        } 
    } 
} 